In DE 101 28 076 A1 and in FIG. 1, a transmission device that is known in the state of the art is shown having a vehicle drive train with a drive machine or rather a combustion engine and an output. The transmission device has an assigned variator, which is designed as a hydrostatic device, for continuous variation of gear ratios of a transmission device. Torque which is provided by a drive machine is introduced into the transmission device by way of a transmission input and is guided from the transmission device in the direction of the output by way of a transmission output shaft.
The torque of the drive machine which is present in the area of the transmission input is introduced, via a first shaft which is designed as a ring gear, into the transmission device through a summing planetary transmission which is designed as a simple planet gear. By means of the summing planetary transmission, so-called power branching of the drive torque of the drive machine is executed, whereby the torque of the first shaft of the summing planetary transmission is brought to an additional shaft on which again planetary gears are rotatably positioned. The planetary gears mesh with a second shaft of the summing planetary transmission which is designed as a sun gear, and which in this case is operationally connected, via a spur gear, with the variator.
On the output side of the transmission, the variator is operationally connected with a transmission shaft which is connected in a rotationaly fixed manner, via a gear chain, through a first shaft of the summing planetary transmission, where the transmission shaft extends essentially with its complete axial length through the transmission device and where at the output side the different users, preferably a construction vehicle or an agricultural vehicle, can be supplied by the drive machine with the torque. Through a spur gear, the second shaft of the summing planetary transmission is coupled with the first shaft of the variator, while the first shaft of the summing planetary transmission is operationally connected, via the shaft and the gear chain, with a second shaft of the variator.
In addition to the summing planetary transmission, a transmission device is presented having three additional planetary transmissions, and five friction locking shift elements of a shift transmission, where friction locking shift elements are friction clutches and another friction locking shift element is a brake.
The first shaft of the summing planetary transmission is connected in a rotationaly fixed manner with a planetary carrier of the first planetary transmission. In addition, the additional shaft of the summing planetary transmission is coupled in a rotationally fixed manner with a planetary carrier of the second planetary transmission and a ring gear of the first planetary transmission. A sun gear of the first planetary transmission is connected in a rotationaly fixed manner with a sun gear of the second planetary transmission.
The planetary carrier of the summing planetary transmission, the ring gear of the first planetary transmission which is connected in a rotationaly fixed manner with it, and also the planetary carrier of the second planetary transmission which is connected in a rotationaly fixed manner with it, can be coupled in a rotationally fixed manner via the third friction locking shift element with a planetary carrier of the third planetary transmission. The planetary carrier of the third planetary transmission is connected in a rotationaly fixed manner with the transmission output shaft. In an engaged operating condition of the fourth friction locking shift element, the additional shaft of the summing planetary transmission, together with the ring gear of the first planetary transmission and the planetary carrier of the second planetary transmission, are coupled in a rotationally fixed manner with a sun gear of the third planetary transmission, while a ring gear of the third planetary transmission, in an engaged operating condition of the brake, is connected in a rotationally fixed manner with a transmission housing mounted part.
When engaging the first friction locking shift element, a ring gear of the second planetary transmission is connected in a rotationaly fixed manner with the sun gear of the third planetary transmission, while the sun gears of the planetary transmissions, when the second friction locking shift element is engaged, are rotationally fixed with the sun gear of the third planetary transmission.
The previously described transmission device is disadvantageously characterized, due to the allocated hydrostatic device, as requiring a large construction are and having a large manufacturing cost. In addition, the transmission device, due to the cooling and lubricant needs of the hydrostatic device for the hydraulic supply system of the transmission device and also due to bearing, gearing, and drag losses, can only be operated in the realm of the hydrostatic power path and in the operational range of the transmission device with an undesired, reduced efficiency. Also, the parts of the transmission device, due to the variator or hydrostatic device vibration excitation, are exposed to a larger load which disadvantageously affects the lifespan.
Also, the transmission device, at lower operating temperatures of the hydrostatic device, can only be operated to its full extent after the hydrostatic device has finished time-consuming warm up phases.